The overall aim of the Clinical Core is to support the projects on three important sexually-transmitted organisms, Trichomonas vaginalis, group B streptococci, and Treponema pallidum. In addition to providing clinical specimens and providing an environment for education and training in sexually transmitted diseases, the Core has specific aims which are logical and important clinical extensions of the projects on T. vaginalis and group B streptococci. In the Core's aim on T. vaginalis, we will determine whether phenotype is related to several clinical measures of virulence (symptoms of infection, persistence or recurrence of infection, or infection in sexual partners). Similarly, in the Core's aim on group B streptococci, we will determine whether the lipoteichoic acid chain type is related to two measures of virulence (persistence of infection and in vitro attachment to vaginal epithelial cells. The clinical studies will be carried out in cohorts of culture positive women. Because these organisms exact a heavy burden, it is pertinent to determine these clinical correlates so that strategies for intervention and control may be advanced.